I. Field
The present disclosure relates generally to improved processes for the production of an adipic acid product. More specifically, it relates to processes for converting a glucose-containing feed derived from a carbohydrate source to an adipic acid product wherein the process comprises the steps of: converting glucose in the feed to a reaction product including a hydrodeoxygenation substrate and a first concentration of water; reducing the concentration of water in the reaction product to produce a feedstock including the hydrodeoxygenation substrate and second concentration of water, wherein the second concentration of water is less than the first concentration of water; and converting at least a portion of the hydrodeoxygenation substrate in the feedstock to an adipic acid product.
II. Description of Related Art
Crude oil is currently the source of most commodity and specialty organic chemicals. Many of these chemicals are employed in the manufacture of polymers and other materials. Examples include ethylene, propylene, styrene, bisphenol A, terephthalic acid, adipic acid, caprolactam, hexamethylene diamine, adiponitrile, caprolactone, acrylic acid, acrylonitrile, 1,6-hexanediol, 1,3-propanediol, and others. Crude oil is first refined into hydrocarbon intermediates such as ethylene, propylene, benzene, and cyclohexane. These hydrocarbon intermediates are then typically selectively oxidized using various processes to produce the desired chemical. For example, crude oil is refined into cyclohexane which is then selectively oxidized to “KA oil” which is then further oxidized for the production of adipic acid, an important industrial monomer used for the production of nylon 6,6. Many known processes are employed industrially to produce these petrochemicals from precursors found in crude oil. For example, see Ullmann's Encyclopedia of Industrial Chemistry, Wiley 2009 (7th edition), which is incorporated herein by reference.
For many years there has been an interest in using biorenewable materials as a feedstock to replace or supplement crude oil. See, for example, Klass, Biomass for Renewable Energy, Fuels, and Chemicals, Academic Press, 1998, which is incorporated herein by reference. Moreover, there have been efforts to produce adipic acid from renewable resources using processes involving a combination of biocatalytic and chemocatalytic processes. See, for example, “Benzene-Free Synthesis of Adipic Acid”, Frost et al. Biotechnol. Prog. 2002, Vol. 18, pp. 201-211, and U.S. Pat. Nos. 4,400,468, and 5,487,987.
One of the major challenges for converting biorenewable resources such as carbohydrates (e.g. glucose derived from starch, cellulose or sucrose) to current commodity and specialty chemicals is the selective removal of oxygen atoms from the carbohydrate. Approaches are known for converting carbon-oxygen single bonds to carbon-hydrogen bonds. See, for example: U.S. Pat. No. 5,516,960; U.S. Patent App. Pub. US2007/0215484 and Japanese Patent No. 78,144,506. Each of these known approaches suffers from various limitations and we believe that, currently, none of such methods are used industrially for the manufacture of specialty or industrial chemicals.
Industrially scalable methods for the selective and commercially-meaningful conversion of carbon-oxygen single bonds to carbon-hydrogen bonds, especially as applied in connection with the production of chemicals from polyhydroxyl-containing substrates (e.g., glucaric acid), and especially for the production of chemicals from polyhydroxyl-containing biorenewable materials (e.g., glucose derived from starch, cellulose or sucrose) to important chemical intermediates such as adipic acid have been reported in U.S. Patent App. Pubs. US2010/0317822 and US2010/0317823, both of which are hereby incorporated by reference in their entireties. In US2010/0317823, processes for the conversion of glucose-containing feed to an adipic acid product via glucaric acid and/or derivatives thereof are reported. Such processes include the steps of catalytic oxidation of the glucose-containing feed to glucaric acid and/or derivatives thereof followed by catalytic hydrodeoxygenation of glucaric acid and/or derivatives thereof to an adipic acid product. The catalytic oxidation step produces 1 mole of water per mole of glucaric acid on a stoichiometric basis and up to 3 moles of water per mole of glucaric acid derivatives such as lactones. Additionally, the feed to the oxidation reactor typically comprises between about 40% and about 90% water on a weight basis. Applicants have discovered that the efficacy of the subsequent hydrodeoxygenation reaction (to which the glucaric acid-containing product from the oxidation reaction is subjected to produce an adipic acid product) can be significantly beneficially affected by reducing the concentration of water in the feed to the hydrodeoxygenation reaction. The reduction of water also significantly reduces the capital cost of downstream purification equipment and the operating costs associated with such purification.